Google maintains that those concerns are unwarranted, saying data is more secure in one of its data centers than in an organization's data center.
Another challenge for Apps' adoption is CIOs' reluctance to change software that tens of thousands of employees use, Girouard said. "The thought of moving 50,000 end-users to an entirely new experience for something they use every day is very daunting," he said.
Every few weeks, a large enterprise with 10,000 end-users or more migrates to Apps, and every time that happens, momentum continues to build, as well as confidence in the suite itself, as well as in the SaaS (software-as-a-service) model, he said.
One thing that doesn't help CIOs understand SaaS specifically and cloud computing in general is the sudden appropriation of the terms by myriad vendors in order to benefit their marketing efforts, he said.
"It's interesting that everybody is in cloud computing now. In most cases, I view it as a re-labeling of what they were doing five years ago," he said.
Girouard has a particular beef with the term "private clouds" to refer to customer data centers that have been optimized through the use of virtualization technology.
"By no means would I describe that as cloud computing. I'd call that more efficient data centers and getting more out of the servers you buy," he said.
Among the few vendors doing true cloud computing at scale are Google, Salesforce.com and Amazon.com, he said.
"If you're still selling large up-front buildouts of X, Y or Z, regardless of what virtualization is involved, that's not in my mind cloud computing," he said.
Google's Enterprise unit generates "a few hundred million dollars" in revenue, is profitable and is growing, Girouard said.
Its revenue is just a small fraction of Google's total revenue, which mostly comes from online advertising, but growing that percentage isn't his focus.
"I'm not competing with the rest of Google. I'm looking to build a very large business over a long period of time," he said.
The opportunities in IT enterprise search and Web-hosted business software are big. "We can be a first-tier player in IT," he said.
"We're not driving Google's top or bottom line in 2009, and probably not in 2010, for that matter. Having said that, we can grow for many years in this business and build a very large business over time," he said.
Sign up for CIO Asia eNewsletters.